Many aircraft are primarily powered by gas turbine engines that require carbon-based fuels such as gasoline or kerosene. These fuels typically contain significant energy for their weight, thereby providing the vast amount of power that is required to lift large commercial airliners on flights of thousands of miles. But with oil resources declining and penalties on greenhouse gas emissions increasing, the future of aviation is dependent on finding alternative power sources. Electric aircraft engines have recently begun being developed in an attempt to replace traditional gas turbine aircraft engines. Electric aircraft engines can rely on battery and other sources of electric power rather than carbon-based fuels thereby significantly reducing harmful emissions in comparison with gas turbine engines.
However, an electric aircraft engine struggles to generate as much thrust as a gas turbine engine. One cause in the reduced amount of thrust is that electric aircraft engines have a fan that is powered by an electrical system while gas turbine aircraft engines have a fan that is driven by a gas turbine which relies on combustion. An electric aircraft engine usually requires additional components such as a battery, generator, etc., which can cause the electric aircraft engine to be heavier than a gas turbine engine. As a result, an electric aircraft engine is less energy dense than a gas turbine engine as a result of the additional weight. Therefore, replacing gas turbine engines on a commercial aircraft with electric aircraft engines is a proposal that faces significant energy-based limitations. In an effort to address these obstacles, it is necessary to improve the overall energy efficiency of the electric aircraft.
Attempts to improve electric aircraft energy consumption include reducing weight of the aircraft and improving aerodynamics thereby generating less drag and optimizing a flight profile. However, electric aircraft engines require a very high-power density design that can overheat and must be cooled quickly or risk overheating. Adding a cooling system to an electric aircraft engine typically adds size, weight, surface area, and/or the like. As a result, a traditional cooling system can reduce the overall energy efficiency of the electric aircraft engine by generating drag. Gas turbines route oil through a conventional heat exchanger which is often a bulky object or fins within the fan stream which then reject the heat off the system. However, these items create an additional drag on the aircraft. This is not an option for an electric aircraft engine which requires improved energy efficiency.